1. Field of the Invention
The present invention relates to a linear motor, and more particularly, to an improved magnet fixing structure for a linear motor, wherein a pair of eddy current loss preventing slits are formed in slant, or a plurality of eddy current loss preventing pores, e.g., are formed, along an outer periphery of a magnet fixing ring which fixes the magnet into a magnet paddle so as to minimize the widening of each slit of the magnet fixing ring, thereby strengthening the fixture of the magnet into the magnet paddle.
2. Description of the Background Art
As shown in FIG. 1A, a moving magnet type motor is connected to a piston (not shown) of a linear compressor. A magnet M is connected into a magnet paddle 1 disposed between an inner lamination 3 and an outer lamination 4 which face against each other. The magnet M makes a high speed linear reciprocal movement between the two laminations 3, 4 in accordance with a magnetic field induced between the inner and outer laminations 3, 4, thereby driving the piston (not shown) connected thereto.
In order for the magnet paddle 1 to constantly make a high speed linear reciprocal movement in such a linear motor, the magnet M should be firmly fixed into the magnet paddle 1 without being deviated therefrom or fluctuated therealong.
Therefore, the magnet fixing structure for a linear motor serves to rigidly fix the magnet M into the magnet paddle 1 so as to prevent the magnet M from being deviated from the magnet paddle 1, thereby determining motor efficiency and reliability during a linear motor design.
According to such a conventional linear motor, a thin cylindrical magnet fixing ring 2 is fixed onto an inner periphery or outer periphery of the magnet M which is fixed into the magnet paddle 1 so as to maintain a stabilized fixture of the magnet M into the magnet paddle 1.
With reference to the accompanying drawings, the magnet fixing structure for the conventional linear motor will now be described.
As shown in FIGS. 1A and 1B, a plurality of magnet insert openings 1a are formed in and along the outer periphery of the cylindrical magnet paddle 1 which has both ends thereof opened and which is thinner than the magnet M so as to be inserted thereinto by the magnet M. The magnet fixing ring 2 is in a cylindrical shape with its both ends opened so as to tightly fix the magnet M into the magnet paddle 1, wherein the magnet M is inserted under pressure into an outer periphery of the magnet paddle 1 as shown in the drawing or an inner periphery of the magnet fixing ring 2.
Referring to FIG. 1B, in order to prevent the magnet M from being overinserted by the pressure of the magnet fixing ring 2 into the opening 1a of the magnet paddle 1 when the magnet M is fixed into the magnet paddle 1 by the magnet fixing ring 2, the magnet M includes a protrusion extended from each side thereof along the peripheral direction of the magnet paddle 1.
Also, as shown in FIG. 2, a plurality of eddy current loss preventing slits 2a, 2a' are formed along an axial direction in the periphery of the cylindrical magnet fixing ring 2 which is a non-magnetic body, so as to prevent the loss of eddy current occurring due to a magnetic induced between the respective laminations 3, 4.
The assembly steps of the magnet fixing structure for the conventional linear motor will now be explained.
The magnet M is appropriately inserted from outside the magnet paddle 1 into each of the magnet insert openings 1a formed in the periphery of the magnet paddle 1 which is connected to the piston (not shown). Then, the cylindrical magnet fixing ring 2 which is non-magnetic is attached under pressure onto the outer periphery (as shown in the drawing) or an inner periphery of the magnet M so as to prevent the magnet M from being deviated from or fluctuated by the magnet paddle 1. The upper and lower end portions of the magnet fixing ring 2 are bent toward the magnet paddle so that the magnet M can not be deviated from or fluctuated by the magnet paddle 1, thereby rigidly fixing the magnet M into the magnet paddle 1 without deviation or fluctuation during the high speed linear reciprocal movement in accordance with a magnet induced between the respective laminations 3, 4.
However, in the magnet fixing structure for the conventional linear motor, since the eddy current loss preventing slits are formed in the periphery of the magnet fixing ring toward an axial direction, the eddy current loss preventing slits may be widened toward a peripheral direction of the ring during the attachment of the magnet onto the outer periphery of the magnet, thereby deteriorating adhesivity thereof with the magnet. Further, the poor adhesivity may cause noise due to an undesirable fluctuation of the structure, thereby damaging the magnet.